A Time-Domain Perspective on the Structural and Electronic Response in Epitaxial Ferroelectric Thin Films on Silicon.

This operando study of epitaxial ferroelectric Pb(ZrTi)O capacitors on silicon substrates studies their structural response via synchrotron-based time-resolved X-ray diffraction during hysteresis-loop measurements in the 2-200 kHz range. At high frequencies, the polarization hysteresis loop is rounded and the classical butterfly-like strain hysteresis acquires a flat dumbbell shape. We explain these observations from a time-domain perspective: The polarization and structural motion within the unit cell are coupled to the strain by the piezoelectric effect and limited by domain wall velocity.

Quantification of Crystalline Phases in HfZrO Thin Films through Complementary Infrared Spectroscopy and Supercell Simulations.

In the quest for thinner and more efficient ferroelectric devices, HfZrO (HZO) has emerged as a potential ultrathin and lead-free ferroelectric material. Indeed, when deposited on a TiN electrode, 1-25 nm thick HZO exhibits excellent ferroelectricity capability, allowing the prospective miniaturization of capacitors and transistor devices. To investigate the origin of ferroelectricity in HZO thin films, we conducted a far-infrared (FIR) spectroscopic study on 5 HZO films with thicknesses ranging from 10 to 52 nm, both within and out of the ferroelectric thickness range where ferroelectric properties are observed.

Low-voltage, broadband graphene-coated Bragg mirror electro-optic modulator at telecom wavelengths.

We demonstrate a graphene based electro-optic free-space modulator yielding a reflectance contrast of 20% over a strikingly large 250nm wavelength range, centered in the near-infrared telecom band. Our device is based on the original association of a planar Bragg reflector, topped with an electrically contacted double-layer graphene capacitor structure employing a high work-function oxide shown to confer a static doping to the graphene in the absence of an external bias, thereby reducing the switching voltage range to +/-1V. The device design, fabrication and opto-electric characterization is presented, and its behavior modeled using a coupled optical-electronic framework.

Publisher Correction: Large anisotropy of ferroelectric and pyroelectric properties in heteroepitaxial oxide layers.

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Large anisotropy of ferroelectric and pyroelectric properties in heteroepitaxial oxide layers.

Epitaxial PbZrTiO (PZT) layers were integrated on Si(001) with single PZT {001} orientation, mosaïcity below 1° and a majority of a-oriented ferroelectric domains (∼65%). Ferroelectric and pyroelectric properties are determined along both the out-of-plane and in-plane directions through parallel-plate capacitor and coplanar interdigital capacitor along the <100> direction. A large anisotropy in these properties is observed.